A new blood test can determine if a child is on the autism spectrum with 96 per cent accuracy, according to American researchers.

Scientists from the Rensselaer Polytechnic Institute in New York have developed a new, highly accurate method that analyses metabolic biomarkers to assess whether a child is on the autism spectrum, according their new study published in PLOS Computational Biology.

Autism spectrum disorder affects about 1.5 percent of all children, but its exact cause remains unknown, and diagnosis requires a multidisciplinary team of doctors.

Previous research has revealed certain differences in metabolic processes between children on the autism spectrum and neurotypical children. However, researchers have struggled to translate these differences into new diagnostic tools.

In the new study, researchers Juergen Hahn and Daniel Howsmon present a method to identify a child as being on the autism spectrum based on concentrations of specific substances found in a blood sample.

These substances are produced by metabolic processes known as the folate-dependent one-carbon (FOCM) metabolism and transulfuration (TS) pathways, both of which are altered in children with autism.

The scientists used blood sample data from 83 children with autism and 76 neurotypical children, all between 3 and 10 years old.

With the help of advanced modelling and statistical analysis tools, the metabolic data allowed the researchers to correctly classify 97.6 per cent of the children with autism and 96.1 per cent of the neurotypical children.

“The method presented in this work is the only one of its kind that can classify an individual as being on the autism spectrum or as being neurotypical,” says study author Juergen Hahn.

“We are not aware of any other method, using any type of biomarker that can do this, much less with the degree of accuracy that we see in our work.”

Hahn says that further research is needed to confirm the findings.

The team is also hoping to study whether treatments could be used to alter the concentrations of FOCM and TS products and, if so, whether this could impact symptoms of autism spectrum disorder.